vtkPolyDataNormals: Fix how links are Build/ShallowCopied and when they are preserved
- vtkPolyDataNormals now always calls BuildLinks to make sure the links are updated.
- vtkOrientPolyData/vtkSplitSharpEdges when shallow copying the links from another dataset first the links are set and then they are shallow copied
- vtkPolyDataNormals does not preserve the links it used for its computation to free-up memory.